Charlatan putting out constant source of error, making you tremble (5)
I believe the answer is:
quake
'tremble' is the definition.
(I know this)
'charlatan putting out constant source of error' is the wordplay.
'charlatan' becomes 'quack' (quack is a kind of charlatan).
'putting out' is a deletion indicator.
'constant' becomes 'c' (mathematical abbreviation).
'source of error' becomes 'e' (I can't explain this - if you can you should believe this answer much more).
'quack' with 'c' removed is 'quak'.
'quak'+'e'='QUAKE'
'making you' is the link.
Can you help me to learn more?
(Other definitions for quake that I've seen before include "Earth tremor" , "Tremble (with fear)" , "Quiver" , "Vibrate" , "Show fear" .)